This invention relates generally to systems and methods for delivering sanitized water and for decontaminating fluid delivery lines. More specifically, the invention relates to a system and method for providing a self-cleaning fluid delivery system. In specific embodiments, the invention is directed to a self-cleaning dental drilling and irrigation system.
The formation of microbial biofilm is a significant problem in fluid delivery systems, particularly those used in dental, medical and food service applications, and various governmental and professional organizations are implementing standards and regulations for addressing this problem. Biofilm buildup occurs when bacteria or other microbes colonize tubing walls of fluid delivery systems. The biofilm forms a slime layer which fosters and protects growing microbes and hinders their removal and treatment. Generally, fluid flow in most delivery systems is laminar, and this favors the build up of biofilm. Biofilm represents a reservoir of contamination, and can support the growth of secondary organisms such as fungi, protozoa and nematodes. Biofilm can dislodge in the course of use of the system, and can present a significant source of infection.
Biofilm build up is of particular concern in medical and dental applications. The problem is compounded because medical and dental fluid delivery systems are frequently highly complex, expensive and thus difficult to clean or replace. Heretofore, biofilm control was attempted by flushing fluid delivery systems with biocidal compositions. This approach has been found to be ineffective. As noted above, fluid flow through such systems is generally laminar; hence, a flowing biocide does not effectively interact with biofilms. These problems are compounded because of the smooth, adherent nature of most biofilms. In fact, such cleaning attempts have been found to encourage the growth of biocide resistant organisms within the biofilm. Highly aggressive cleaning compositions such as alkalis, acids or the like generally cannot be used in complex medical and dental fluid delivery systems, since such aggressive chemicals can damage sensitive components of the systems; furthermore, residues from such aggressive chemicals can present a hazard to patients. In view of the general ineffectiveness of such chemical treatment methods, the only other approach heretofore available was to disassemble and manually clean and/or replace components of the system. This approach is clearly very expensive and time consuming. Furthermore, new biofilm buildup occurs fairly rapidly.
U.S. Pat. No. 5,556,279 discloses a system which employs iodine for purifying water supplied to a dental unit. The purified water limits the activity of microorganisms; however, it cannot completely stop biofilm buildup and does not function to remove biofilms which are already in place. Another approach to the problem of biofilms in dental systems is disclosed in U.S. Pat. No. 6,212,333. The system disclosed therein employs heat to sanitize incoming water. This sanitized water is then delivered by a pump to a dental workstation. Again, while the system of the ""333 patent does sanitize water, this sanitized water is ineffective against biofilms already in the dental unit. Also, even though the water is heat sanitized, there is typically some residual biological activity which can initiate or contribute to biofilm growth.
Clearly, there is a need for a system and method which can provide sanitized water to a dental unit or other such workstation, and which can further function to remove biofilm buildup therefrom. Ideally, biofilm removal should not require any disassembly of the fluid delivery system and should be accomplished without the use of corrosive or otherwise dangerous chemicals. As will be explained hereinbelow, the present invention comprises a system which is operable to provide sanitized water to a fluid delivery system and which is further operable to destroy and remove biofilms from that system. The sanitization process of the present invention is accomplished through the use of steam. The sanitization process of the present invention does not require disassembly of the equipment being sanitized, and hence is very useful for cleaning fluid delivery systems associated with dental and medical equipment such as drill motors, dialysis units and the like. The system of the present invention is simple in design and low in cost and can be incorporated into specific workstations or equipment.
It is to be understood that while the system of the present invention is described and discussed herein with regard to dental and medical equipment, the benefits and advantages of the present invention will make it readily adaptable to all systems which require the delivery of sanitized fluid, and which are prone to biofilm buildup. As such, the present invention finds utility in connection with water coolers, beverage vending machines, soft drink and beer delivery systems, bottling systems and other food processing and delivery equipment. Biofilm buildup is also of concern in various industrial processes wherein microbial contamination can contaminate products or interfere with processing, and the present invention may be readily incorporated thereinto. In view of the teaching presented herein, it is to be understood that this invention may be employed in any application wherein there is a need to control and/or remove biofilm buildup in fluid systems. These and other advantages of the invention will be apparent from the drawings, discussion and description which follow.
There is disclosed herein a self-cleaning system for delivering sanitized water to a workstation, such as a dental unit. The system includes a boiler which is connectable to a source of water by a water inlet and which is operable to provide steam and heat sanitized water. The system may optionally include a sanitized water reservoir which is integral with, or in fluid communication with, the boiler. The system further includes a sanitized water delivery line and a steam delivery line in fluid communication with the boiler, as well as a fluid delivery line. A diverter valve is in fluid communication with the sanitized water delivery line, the steam delivery line and the fluid delivery line, and is operable to selectively establish fluid communication between the fluid delivery line and either the steam delivery line or the sanitized water delivery line. In this manner, either sanitized water or steam may be delivered to the fluid delivery line. When steam is supplied to the line, this steam will function to destroy and remove biofilm contamination.
In further embodiments of the present invention, a heat exchanger is disposed so as to cool the heat sanitized water coming from the boiler. The excess heat removed by the heat exchanger may be used to warm input water to the boiler and/or to heat a stream of air. In specific embodiments, the boiler operates at a pressure above atmospheric, typically 1.5 to 2.0 atmospheres, and the steam pressure generated thereby may be employed to move the sanitized water through the system without the aid of a pump.
The system of the present invention may further include water softeners, filters or other conditioners associated with the water input line. In certain embodiments, the system may be further adapted to selectably introduce a biocidal composition into the fluid delivery line, and this biocide may be used in conjunction with the steam to aid in cleaning and sanitizing the fluid delivery system.